This invention relates to an actuator for controlling brake hydraulic pressure to be mounted in a vehicle hydraulic brake system such as an anti-lock brake system (ABS) or a vehicle stability control (VSC) system, and a device and a method for inspecting such an actuator.
As shown in FIG. 8 and disclosed in unexamined JP patent publication 2001-260846, such a brake system includes an actuator 3 for controlling brake hydraulic pressure provided between a brake pedal 1 and brake wheel cylinders 4a–4d. The actuator 3 comprises control valves for pressure increase and reduction, respectively, that are mounted in a housing. By selectively turning on and off these control valves, hydraulic pressure to be supplied to the brake wheel cylinders 4a–4d can be controlled.
Today, there are a vast variety of such vehicle hydraulic brake systems, including those having anti-lock control and/or vehicle stability control functions. Different brake systems need different kinds of actuators. Today's such actuators comprise a far greater number of component parts than older ones. It is therefore acutely desired that each of the component parts forming the actuator be as small as possible.
FIG. 9 shows a compact brake unit disclosed in unexamined JP patent publication 08-11696 and comprising a hydraulic brake booster 5, an actuator 3 for controlling brake hydraulic pressure mounted to the booster 5, and a master cylinder 2. A brake pedal 1 is coupled to a piston rod 5a of the master cylinder 2. The housing 10 of the actuator 3 is integral with the body 30 of the master cylinder 2. Control valves for pressure increase and pressure reduction and other elements of the actuator 3 are mounted in the housing 10. Pipes r run from the housing 10 to the brake wheel cylinders 4a–4d. 
Before shipment to a car manufacturer (to its assembly factory), the actuator 3 is inspected for its hydraulic performance. As shown in FIGS. 12 and 13, the inspection is conducted by sending a plurality of such actuators 3 one by one into an inspection device 40, in which port couplers 41 are connected to respective wheel cylinder ports 17 of each actuator 3, and hydraulic pressure or air pressure is introduced into the actuator 3 through the couplers 41 and the ports 17.
If the actuator 3 is the one used in an ABS, it usually has four wheel cylinder ports 17, of which two are provided in the front end wall of the housing 10 of the actuator (which is also the body of the master cylinder 2) and the other two are provided in the right-hand side wall thereof, as shown in FIGS. 10A and 10B.
Four pipes r extend from the respective ports 17 to the respective wheel cylinders 4a–4d as shown in FIG. 8. In either of a vehicle with the steering wheel (and thus the brake pedal) arranged on the right-hand side of the vehicle (FIG. 10A) and a vehicle with the steering wheel on the left (FIG. 10B), the actuator 3 is mounted in the engine room such that the space between the side wall of the engine room and the actuator 3 is greater than the space between the engine 6 and the actuator 3. Thus, in the case of a vehicle with the steering wheel on the right, there exists a large space between the ports 17 formed in the right-hand side wall of the housing 10 of the actuator 3 and the right-hand side wall of the engine room. Thus, the pipes r can be easily connected to these ports 17. In the case of a vehicle with the steering wheel on the left, however, there exists only a narrow space between the ports 17 formed in the right-hand side wall of the actuator 3 and the engine 6. Thus, it is difficult or sometimes impossible to connect the pipes r to these ports 17.
In order to connect the pipes r to the ports 17 formed in the right-hand side wall of the housing 10 of the actuator 3 mounted in a vehicle with the steering wheel on the left, the pipes r are sometimes connected to these ports 17 through union connectors 20 as shown in FIG. 11A. As shown in FIG. 11B, each union connector 20 comprises a bolt 21 formed with a passage and threadedly engaged in one of the ports 17, and a union member 22 pivotally mounted on the protruding end of the bolt 21 such that the passage formed therein communicates with the passage formed in the bolt 21. A pipe r is connected to the union member 22. Since the union member 22 of each union connector 20 is pivotable relative to the bolt 21, the pipes r connected to the ports 17 on the right-hand side wall of the actuator 3 can be arranged so as to extend forwardly (the direction indicated by the arrow of FIG. 11A) of the vehicle through the narrow space between the actuator 3 and the engine 6. But use of such union connectors 20 is extremely troublesome. Mounted in the engine room besides the engine 6 are an engine cooling fluid tank 7a, a windshield washing water tank 7b, a battery 8, a relay box 8a and an air cleaner 9.
FIG. 9 shows another conventional arrangement in which all four ports 17 are formed along one side wall of the housing 10. If the ports 17 are formed along the right-hand side wall of the housing 10, they will face the engine 6 of a vehicle with the steering wheel on the left, and if the ports 17 are formed along the left-hand side wall of the housing 10, they will face the engine 6 of a vehicle with the steering wheel on the right. Thus, in either case, the same problem mentioned above with reference to FIGS. 10A and 10B will arise.
One way to solve this problem would be to prepare two kinds of actuators, one for a vehicle with the steering wheel on the right, which has all or some of their ports 17 formed in the right-hand side wall of the housing 10, and the other for a vehicle with the steering wheel on the left, which has all or some of their ports 17 formed in the left-hand side wall of the housing. But preparing two different kinds of actuators is troublesome and thus will push up the cost.
In order to dismount the pipes r from the respective ports 17 for repair and subsequently re-mount them to the ports 17, a spanner having a long handle as shown at 50 in FIG. 5 has to be used. When such a spanner is turned in the space between the housing 10 and the side wall of the engine room or the engine 6 to attach and detach pipes r to and from the ports 17 formed in one of the side walls of the housing 10, the spanner tends to interfere with the relay box 8a or the engine 6.
Preferably, an inspection for hydraulic performance of such actuators 3 is conducted automatically for higher productivity. As described above and as shown in FIGS. 12 and 13, this inspection is conducted by sending a plurality of such actuators 3 one by one into the inspection device 40, in which the port couplers 41 are connected to the respective wheel cylinder ports 17 of each actuator 3, and hydraulic pressure or air pressure is introduced into the actuator 3 through the couplers 41 and the ports 17.
The actuators 3 are transported on a conveyor 51. If the actuators inspected are of the type having their wheel cylinder ports 17 formed both in the front wall and one of the side walls thereof, it is necessary to provide the inspection device 40 with two jigs 42 for automatically connecting the port couplers 41 to the respective ports 17. As shown in FIG. 12, the two jigs 42 have to be provided so as to reciprocate in directions perpendicular to each other. Such jigs take up much space and thus increase the size of the inspection device 40, especially its length L.
The wheel cylinder ports 17 of the actuators 3 shown in FIG. 13 have different lengths and are oriented in different directions from each other because one of them carries a union connector 20 as shown in FIG. 11B, while the others do not. Thus, jigs 42 shown in FIG. 12 cannot be used to automatically connect the port couplers 41 to the respective ports 17. The couplers 41 have to be manually connected to the respective ports 17 instead. This is troublesome and inefficient.
An object of the present invention is to provide an actuator for a vehicle hydraulic brake system which can be mounted in either of a vehicle having its steering wheel arranged on its right and a vehicle having its steering wheel arranged on its left such that enough space is provided in the engine room for arranging pipes for connecting its wheel cylinder ports to the respective wheel cylinders and for mounting and dismounting the pipes from the wheel cylinder ports, and a method and a device for inspecting such actuators in a smooth and efficient way.